SPX Reference Manual
8
Digital I/O
Description
The SPX-2 provides a 16-channel digital I/O interface. The digital lines are grouped as two 8-bit
bi-directional ports. Data direction and output driver type are configurable by software.
Input data can be inverted through register settings. Any I/O pin(s) can generate an interrupt on
change of state. As outputs, the I/O pins drive at 3.3 volt CMOS levels. The SPX-2 I/O inputs are
not 5 volt tolerant. Inputs have external 10k pull-ups to 3.3 volts.
The digital I/O expander communicates with the host computer through the SPX interface.
E
XTERNAL
C
ONNECTIONS
Digital I/O channels 0-15 are accessed via connectors J2 through J5 of the SPX-2 as shown in the
following table.
Table 4: Digital I/O Connectors
J2
Pin
Signal
Name
Description
1
GPA0
Digital I/O 0
2
GPA1
Digital I/O 1
3
GPA2
Digital I/O 2
4
GPA3
Digital I/O 3
5 Ground Ground
J3
1
GPA4
Digital I/O 4
2
GPA5
Digital I/O 5
3
GPA6
Digital I/O 6
4
GPA7
Digital I/O 7
5 Ground Ground
J4
1
GPB0
Digital I/O 8
2
GPB1
Digital I/O 9
3
GPB2
Digital I/O 10
4
GPB3
Digital I/O 11
5 Ground Ground
J5
1
GPB4
Digital I/O 12
2
GPB5
Digital I/O 13
3
GPB6
Digital I/O 14
4
GPB7
Digital I/O 15
5 Ground Ground
3
